Crop Profile for Corn (Sweet) in Illinois
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Crop Profile for Corn (Sweet) in Illinois Prepared October, 2000 General Production Information Production Facts(1992) Processed Sweet Corn Acres Used: 38,900 Value of Production: $15,7000,000 Fresh Market Sweet Corn Acres Used: 8,000 Value of Production: $8,800,000 Number of Operations: 288 Cultural Practices Sweet corn is grown throughout Illinois. Reported acres are mainly those where the crop is sold for commercial use. An undetermined number of sweet corn acres is used for fresh market sweet corn as roadside stands are popular within the state. Sweet corn is planted on similar schedule as field corn. Fields are generally tilled as weed competition decreases with tillage and the need for herbicide treatments also decrease. Sweet corn fields may also be fertilized similar to field corn. Commercial acres are treated with pesticides similarly to field corn with the exception that weed treatments occur mainly at preemergence. Insect control is very important due to consumer intolerance at the time of purchase. Sweet corn is harvested before any kernal denting occurs. Small acreages employ manual labor for hand picking ears from the plant. Larger commercial acreages use mechanical means to harvest the ears before maturity so that the kernals remain tender. For processed sweet corn, much of the harvest is iced The Crop Profile/PMSP database, including this document, is supported by USDA NIFA. to retain high sugar content within the kernals before reaching the processing facilities. Over mature crops may be harvested as cattle fodder or used for corn silage. In a typical year, the major insect pests can cause severe economic damage in 15% or more of the total acreage. The type of injury that each pest inflicts is different, and the occurrence of the insect and damage caused by each insect vary significantly from year to year and region to region. Crop Loss and % of Area Infested by Insects % Acres Acres Common Name Scientific Name Loss* Infested* Black Cutworm Agrotis ipsilon 5% 14,204 Corn Earworm Helicoverpa zea 4% 39,306 Corn Leaf Aphids Rhopalosiphum maidis 12.5% 8,522 Corn Rootworm, Northern Diabrotica barberi Corn Rootworm, Western Diabrotica virgifera 0.4% 53,522 European Corn Borer Ostrinia nubialis 2.2% 54,997 Fall Armyworm Spodoptera frugiperda 2.1% 32,098 Flea Beetles Disonycha triangularis Japanese Beetle Popillia japonica Sap Beetle Carpophilus lugubris (Murray) *Based on U.S. Averages Black Cutworm Black cutworm adult moths migrate to southern Illinois from March-May and lay eggs in vegetation in or around cornfields. The eggs hatch and larvae feed on available vegetation, Earlier instars feed on corn leaves; later instars cut the plants off near the ground. Fields subject to cutworm infestation often have preplant infestations of weeds, heavy surface debris, poor drainage, or a history of cutworm damage. An annual average of 3% of all fields are treated with post harvest insecticides, and up to 7% of acreage is treated with preplant or preplant-incorporated insecticide applications. Postemergence rescue treatments are justified when 3% or more of plants are cut and larvae are still present; preventative treatments are best utilized in no-till systems or where cutworm damage forces replanting of field. The most harmful cutworms, including the black cutworm, are those that cut off and feed on young seedlings. Young cutworm larvae (first through third instars) are very small, and the larvae feed primarily on corn leaves. This injury is not economic. Older cutworm larvae (fourth and later instars) cut the plants off at, just below, or just above the soil surface. If the growing point is destroyed or the plant is cut below the growing point, the plant will not survive. Large numbers of black cutworms can drastically reduce the plant populations. Although some growers apply soil insecticides to prevent an infestation of cutworms, this practice is usually not justified economically throughout most of the Corn Belt. Densities of cutworms are sporadic and difficult to predict. Consequently, most growers now scout their cornfields, looking for the presence of cutworms and their injury, and apply a "rescue" or therapeutic insecticide if the numbers of cutworms found exceed established economic thresholds. Corn Earworm The adult earworms are about 1/4 inch long and have a wing span of 1-1.5 inches. Their color ranges from green, to tan, to dark brown. Females deposit eggs on the foliage, where they hatch within 5-7 days. The egg laying occurs throughout the sweet corn growing season. Larvae cause damage to the corn by feeding deep inside the whorls, causing holes that measure 1-2 inches across. Proper timing for applying chemical controls is critical. Begin to treat sweet corn during the silkening stage, at the start of egg hatch. Corn Leaf Aphids Winged corn leaf aphids are blown into Illinois by the prevailing winds. Hot, dry weather is unfavorable for natural enemies and can lead to severe infestations of aphids, Heavy infestations will wilt, curl, and cause necrosis of the upper leaves. Aphids excrete honeydew, which coats leaves and reproductive structures and may interfere with pollination. Certain varieties of corn favor aphid survival and may have up to 9 generations a year. Corn Rootworm, Northern and Corn Rootworm, Western The larvae of corn rootworm beetles cause the most economic damage every year in Illinois. The larvae overwinter in the soil and undergo three instars while feeding on corn roots, causing lodging and reducing nutrient and water uptake. It is estimated that of the 11,200,000 acres in Illinois corn about 200,000 acres are treated annually for corn rootworm. The corn rootworm complex consists of four species: Mexican corn rootworm (Diabrotica virgifera zeae Krysan & Smith), northern corn rootworm (D. barberi Smith & Lawrence), southern corn rootworm (D. undecimpunctata howardi Barber), and western corn rootworm (D. virgifera virgifera). Corn rootworm larvae chew on and tunnel inside or along the roots during the summer months. As they feed, the larvae prune roots back to the stalk. Extensive feeding weakens the root systems. Injured plants cannot take up water and nutrients efficiently and are susceptible to lodging. Yield losses are a result of both root pruning and lodging. Management of corn rootworms is usually accomplished by crop rotation or the use of soil insecticides to prevent severe injury to the roots. A corn-soybean rotation usually provides excellent control of rootworm larvae because the larvae survive only on corn roots, rootworm adults do not lay many eggs in soybeans, and rootworms complete only one generation each year. A corn-soybean rotation may fail to control rootworms when volunteer corn plants in a soybean field attract egg-laying beetles or when rootworms exhibit prolonged diapause, a biological phenomenon that allows some eggs, primarily those of northern corn rootworms, to remain dormant in the soil for more than one winter. This trait has become more common in Illinois within the last few years. Corn planted after corn is susceptible to injury by corn rootworm larvae, depending upon the size of the rootworm population. Most producers who grow corn after corn in the Corn Belt usually apply a soil insecticide at planting time to protect the corn roots from larval feeding injury. Most growers apply granular insecticides in either a seven-inch European corn borer First generation corn borer larvae feed on foliage and bore into the stems of whorl-stage plants. Second- generation larvae tunnel into ears, ear stalks, and stalk which causes breakage, lodging, stress, and can significantly reduce yield. It has been estimated that at least 10% of cornfields are infested every year by 3 or more larvae per plant, and that this level of damage causes an estimated 9 to 16% yield loss annually. Annually, from 2-5% of acres are treated in Illinois for corn borer. During outbreak years, as many as 1 millions acres have been treated. Fall Armyworm Fall Armyworms overwinter in southern states because they cannot overwinter in locations where the ground freezes. Larvae range in color from light tan to black. They have a distinct inverted Y on the front of their head capsule. Fall Armyworms reach lengths of 1-11/2 inches. Flea Beetle The different species of flea beetles include the potato flea beetle, the threespotted flea beetle, and the palestriped flea beetle. The potato beetle is a small shiny black beetle. The threespotted beetle has an orange colored thorax which has three dark spots on it. The palestriped beetle is dark brown and has two ivory colored stripes running vertically down its wings. All flea beetles have enlarged hind legs which allow them to jump when disturbed. Flea beetles cause damage to sweet corn as they feed on the leaves. They leave numerous amounts of small holes behind, which can cause the sweet corn to die. In order to control the beetles, fields should be kept weed-free, particularly of field bindweed and mustard, as they are prefered hosts of flea beetles. Japanese beetle The japanese beetles are very strong fliers. They are about 5/8 inch long and overwinter as a larva or grub in soil. In most cases, it's around July when the adults emerge from the soil in great numbers and feed heavily upon foliage. Soaking rains can also cause damage, as it urges successive invasions by the beetles. If effective insecticides are not used, or used in time, beetles from afar will tend to make their way to the fresh vegetables. Sap Beetle As an adult, the sap beetle overwinters in soil or debris. The adult sap beetle is usually 1/8 inch long, and black. The adults feed on ripening pollen and chew tassels. The larvae can cause damage by eating into the kernels of roasting ears.